JRC2010-36215 POLYURETHANE COATING OF RAILROAD BALLAST AGGREGATE FOR IMPROVED PERFORMANCE

ABSTRACT This paper presents preliminary findings of a new technology currently being tested in a research project at the University of Illinois. The effectiveness of elastomer polyurethane coating of ballast is evaluated for its ability to reduce aggregate breakage and resulting ballast fouling. Railroad ballast degradation and fouling related to aggregate breakdown under heavy axle loads, poor drainage, mud pumping, and water/ballast pockets are among the most commonly encountered track substructure (ballast, subballast, and subgrade soil) problems. The structural integrity of seriously fouled ballast can be compromised leading to track instability and ultimately, train derailments. Because of this serious consequence, costly ballast maintenance activities, such as undercutting, tamping, and shoulder cleaning, are routinely performed by railroads especially on tracks serving the heavy axle load unit trains. In the research project, clean AREMA No.4 aggregates along with the polyurethane coated particles were subjected to realistic field loading conditions in a large shear box test apparatus used for strength testing of ballast at full gradation. The urethane coated ballast was allowed to set for 1, 3, 7, and 14 days prior to subjecting the samples up to 10 shear passes. Shear and normal stress data were gathered during testing; and the fines generated by all tested samples were collected and analyzed. Early findings show a major increase in the shear strength gained with the polyurethane coating, a decrease in the breakdown of the coated ballast, and a decrease in particle reorientation which could lead to a reduction in ballast settlement

Automated Track Change Detection Technology for Enhanced Railroad Safety Assessment

693JJ619C000004The Rail Transportation and Engineering Center at the University of Illinois at Urbana-Champaign and Railmetrics, Inc. evaluated the use of 3D laser scanning, Deep Convolutional Neural Networks (DCNNs), and change detection technology for railway track safety inspections. Researchers evaluated the potential use of these combined technologies to provide value-added inspection data to traditional track inspection methods. The project was conducted between April 2019 and October 2020. Field testing was completed on the High Tonnage Loop at the Transportation Technology Center in Pueblo, Colorado

Track Modulus Assessment of Engineered Interspersed Concrete Sleepers in Ballasted Track

Ballasted railway track is typically constructed using sleepers that are manufactured from a common material type within a given length of track. Timber and concrete are the two most common sleeper materials used internationally. Evidence from historical installations of interspersed concrete sleepers in timber sleeper track in North America has indicated inadequate performance, due largely to the heterogeneity in stiffnesses among sleepers. Theoretical calculations reveal that interspersed installation, assuming rigid concrete sleepers and supports, can result in rail seat forces more than five times as large as the force supported by the adjacent timber sleepers. Recently, engineered interspersed concrete (EIC) sleepers were developed using an optimized design and additional layers of resiliency to replace timber sleepers that have reached the end of their service lives while maintaining sleeper-to-sleeper stiffness homogeneity. To confirm that the concrete sleepers can successfully replicate the stiffness properties of the timber sleepers installed in track, field instrumentation was installed under revenue-service train operations on a North American commuter rail transit agency to measure the wheel–rail vertical loads and track displacement. The results indicated that there are minimal differences in median track displacements between timber (2.26 mm, 0.089 in.) and EIC sleepers (2.21 mm, 0.087 in). Using wheel-load data and the corresponding track displacements associated with each wheel load, track modulus values were calculated using the single-point load method based on beam on elastic foundation (BOEF) fundamentals. The calculated values for the track modulus indicated similar performances between the two sleeper types, with median values of 12.95 N/mm/mm (1878 lbs./in./in.) and 12.79 N/mm/mm (1855 lbs./in./in.) for timber sleepers and EIC sleepers, respectively. The field results confirmed the suitability of the new EIC sleeper design in maintaining a consistent track modulus for the location studied, thus evenly sharing loads between and among sleepers manufactured from both concrete and timber

Development of a Real-Time Wheel Load Quantification System for the Transit Environment

With recent (prepandemic) growth in both transit ridership and the number of passenger rail systems nationwide, researchers have been increasingly interested in quantifying the rail transit loading environment. Research that stemmed from this renewed interest provided engineers with greater insights into the loading demands placed on the track structure of heavy, light, and commuter rail systems. Although results from this earlier work were useful in a general manner, it was not possible to provide agencies with immediately actionable information on wheel loads, since the relevant data were analyzed and reported at a later date. As a result, agencies were unable to monitor their rolling stock wheel health in real time. In addition, trend analysis was not possible because it was not feasible to track specific wheels over time. To address these limitations, researchers at the University of Illinois have developed an economical system that both provides real-time notifications to transit agencies when it detects problematic loading conditions, and tracks specific wheels over time. This paper provides a framework for installing and launching this real-time wheel health monitoring system that transit agencies can replicate, as well as presents some preliminary data that have been collected. By receiving actionable wheel load data and better understanding the wheel deterioration trends present on their networks, agencies can remove bad actor wheels from service before they damage the track structure, improving the state of good repair. In addition, a more thorough understanding of the loading environment will allow them to plan maintenance and design more effectively

The Yersinia pseudotuberculosis Cpx envelope stress system contributes to transcriptional activation of rovM

The Gram-negative enteropathogen Yersinia pseudotuberculosis possesses a number of regulatory systems that detect cell envelope damage caused by noxious extracytoplasmic stresses. The CpxA sensor kinase and CpxR response regulator two-component regulatory system is one such pathway. Active Cpx signalling upregulates various factors designed to repair and restore cell envelope integrity. Concomitantly, this pathway also down-regulates key determinants of virulence. In Yersinia, cpxA deletion accumulates high levels of phosphorylated CpxR (CpxR~P). Accumulated CpxR~P directly repressed rovA expression and this limited expression of virulence-associated processes. A second transcriptional regulator, RovM, also negatively regulates rovA expression in response to nutrient stress. Hence, this study aimed to determine if CpxR~P can influence rovA expression through control of RovM levels. We determined that the active CpxR~P isoform bound to the promoter of rovM and directly induced its expression, which naturally associated with a concurrent reduction in rovA expression. Site-directed mutagenesis of the CpxR~P binding sequence in the rovM promoter region desensitised rovM expression to CpxR~P. These data suggest that accumulated CpxR~P inversely manipulates the levels of two global transcriptional regulators, RovA and RovM, and this would be expected to have considerable influence on Yersinia pathophysiology and metabolism